Add a validation mode that diregards all recursive locking errors.
This is useful for locks like lock_page where there is a high degree
of nested locking.
Obviously it will not report a useful class of errors :-/
Signed-off-by: Peter Zijlstra <[email protected]>
---
include/linux/lockdep.h | 15 ++++++++-------
kernel/lockdep.c | 15 ++++++++++++---
2 files changed, 20 insertions(+), 10 deletions(-)
Index: linux-2.6/include/linux/lockdep.h
===================================================================
--- linux-2.6.orig/include/linux/lockdep.h
+++ linux-2.6/include/linux/lockdep.h
@@ -286,7 +286,8 @@ extern void lockdep_init_map(struct lock
*
* 0: disabled
* 1: simple checks (freeing, held-at-exit-time, etc.)
- * 2: full validation
+ * 2: validation without recursion checks
+ * 3: full validation
*/
extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
int trylock, int read, int check, unsigned long ip);
@@ -426,7 +427,7 @@ static inline void print_irqtrace_events
#ifdef CONFIG_DEBUG_LOCK_ALLOC
# ifdef CONFIG_PROVE_LOCKING
-# define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, i)
+# define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 3, i)
# else
# define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, i)
# endif
@@ -438,8 +439,8 @@ static inline void print_irqtrace_events
#ifdef CONFIG_DEBUG_LOCK_ALLOC
# ifdef CONFIG_PROVE_LOCKING
-# define rwlock_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, i)
-# define rwlock_acquire_read(l, s, t, i) lock_acquire(l, s, t, 2, 2, i)
+# define rwlock_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 3, i)
+# define rwlock_acquire_read(l, s, t, i) lock_acquire(l, s, t, 2, 3, i)
# else
# define rwlock_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, i)
# define rwlock_acquire_read(l, s, t, i) lock_acquire(l, s, t, 2, 1, i)
@@ -453,7 +454,7 @@ static inline void print_irqtrace_events
#ifdef CONFIG_DEBUG_LOCK_ALLOC
# ifdef CONFIG_PROVE_LOCKING
-# define mutex_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, i)
+# define mutex_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 3, i)
# else
# define mutex_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, i)
# endif
@@ -465,8 +466,8 @@ static inline void print_irqtrace_events
#ifdef CONFIG_DEBUG_LOCK_ALLOC
# ifdef CONFIG_PROVE_LOCKING
-# define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, i)
-# define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 2, i)
+# define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 3, i)
+# define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 3, i)
# else
# define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, i)
# define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 1, i)
Index: linux-2.6/kernel/lockdep.c
===================================================================
--- linux-2.6.orig/kernel/lockdep.c
+++ linux-2.6/kernel/lockdep.c
@@ -2176,7 +2176,7 @@ static int __lock_acquire(struct lockdep
struct task_struct *curr = current;
struct lock_class *class = NULL;
struct held_lock *hlock;
- unsigned int depth, id;
+ unsigned int depth, id, first;
int chain_head = 0;
u64 chain_key;
@@ -2225,6 +2225,14 @@ static int __lock_acquire(struct lockdep
return 0;
hlock = curr->held_locks + depth;
+ if (check == 2 && depth > 0) {
+ struct held_lock *prev_hlock = NULL;
+
+ prev_hlock = curr->held_locks + depth - 1;
+ if (prev_hlock->class == class)
+ first = 0;
+ } else
+ first = 1;
hlock->class = class;
hlock->acquire_ip = ip;
@@ -2238,7 +2246,7 @@ static int __lock_acquire(struct lockdep
hlock->holdtime_stamp = sched_clock();
#endif
- if (check != 2)
+ if (check < 2)
goto out_calc_hash;
#ifdef CONFIG_TRACE_IRQFLAGS
/*
@@ -2347,7 +2355,8 @@ out_calc_hash:
* graph_lock for us)
*/
#ifdef CONFIG_PROVE_LOCKING
- if (!trylock && (check == 2) && lookup_chain_cache(chain_key, class)) {
+ if (!trylock && (check >= 2 && first) &&
+ lookup_chain_cache(chain_key, class)) {
/*
* Check whether last held lock:
*
--
-
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